Stress Engineering of SiNx Films for Modifying Optical and Mechanical Properties

Abstract

This article presents an approach for the adjustment of residual stress in silicon nitride (SiNx) films by constructing a composite multilayer structure. Curvature and Raman measurement results indicate that with the introduction of a 240-nm-thick SiO2 sublayer, the residual stress in a 110-nm-thick SiNx film varies dramatically from high tensile stress (+358 MPa) to low compressive stress (−57 MPa). The adjustment of film stress leads to the improvement of film quality and the increase of refractive index. However, it also leads to the decreases of Young’s modulus and film hardness of SiNx. Particularly, the optical band gap of SiNx remains almost unchanged during the process. This work demonstrates the practical feasibility of modifying the physical properties of SiNx with the film stress, and suggests a new physical route to stress engineering of SiNx films for microelectronic and optoelectronic applications.